Vegetation cover change and driving factors in the agro-pastoral ecotone of Liaohe River Basin of China from 2010 to 2019

Abstract: Driving mechanisms of Fractional Vegetation Cover (FVC) can be a prerequisite for decision-making on vegetation restoration and management. As the intersection of farming and animal husbandry activities in China, the Liaohe River basin is of great significance for the regional ecological construction and environmental protection, in order to clarify the internal vegetation change characteristics and driving mechanisms. Much effort has been made into the characteristics and influencing factors of vegetation change in the region. However, it is still lacking in the spatial heterogeneity of vegetation in the region as an Agro-pastoral intersection zone. Since vegetation change is a complex process, it is very necessary to fully consider the complex influence of the interaction between environmental factors on vegetation change, rather than only the individual factors. In this study, the spatial heterogeneity of FVC was analyzed in the Liaohe River Basin from 2010 to 2019 using the Normalized Difference Vegetation Index derived from the MOD13Q1 product. Furthermore, the factor regression and interaction were combined to jointly explore the effects of natural and socioeconomic factors on the vegetation changes from a regional and overall perspective. The results showed that: 1) There was an overall rising trend of FVC, with a 10-year average FVC of 0.68 and an overall high level of vegetation cover. The most significant was ranked in the order of the pastoral areas > agricultural areas > semi-pastoral areas, and the vegetation improvement trend in the pastoral areas, in terms of the rising trend of vegetation cover. 2) The explanatory power of natural factors on the vegetation changes in the whole basin was greater than that of human factors, among which the explanatory power of precipitation was the most significant. At the same time, there was an outstanding synchronization between the vegetation and precipitation change, where this trend was the most significant in the pastoral areas. 3) The interaction indicated that most factors showed a mutually reinforcing and non-linear enhancement of vegetation change. It infers that the vegetation change was a complex process with multi-factor effects from a system perspective. There were no completely independent factors. The three largest groups of interacting factors across the basin were the precipitation and temperature, precipitation and elevation, and precipitation and wind speed. The natural factors dominated the interaction of vegetation in the pastoral and semi-pastoral areas. By contrast, a combination of natural and human activities significantly affected the vegetation change in the agricultural areas. 4) The precipitation gradient greatly contributed to the explanation degree of FVC spatial heterogeneity. The environmental factors better fitted the FVC with the increase in precipitation. The precipitation was an important catalyst for the vegetation change. 5) human activities also posed an important influence on the vegetation change. The positive effects of human activities were generally dominant in the study area over the past 10 years. Such reasonable human activities can be maintained to increase the FVC in the Liaohe River basin.